Surface treatment of a semiconductor light emitting device

Abstract

A method according to embodiments of the invention includes roughening (FIG. 6 ) a surface ( 58 ) of a semiconductor structure ( 46 - 48 , FIG. 5 ). The semiconductor structure includes a light emitting layer ( 47 ). The surface ( 58 ) is a surface from which light is extracted from the semiconductor structure. After roughening, the roughened surface is treated (FIG. 7 ) to increase total internal reflection, or absorption at the surface, or to reduce an amount of light extracted from the semiconductor structure through the surface ( 58 ).

What is being claimed is: 
     
       1. A method comprising:
 roughening a light extracting surface of a semiconductor structure, the semiconductor structure comprising a light emitting layer; and 
 after the roughening, treating the surface to significantly reduce an amount of light extracted from the light extracting surface by increasing at least one of: total internal reflection within the semiconductor structure, and absorption at the surface. 
 
     
     
       2. The method of  claim 1  wherein treating the surface comprises treating the surface with plasma. 
     
     
       3. The method of  claim 2  wherein the plasma comprises at least one of Ar and O. 
     
     
       4. The method of  claim 1  further comprising:
 growing the semiconductor structure on a growth substrate; 
 attaching the semiconductor structure to a mount; and 
 removing the growth substrate; 
 wherein the light extracting surface is a surface revealed by removing the growth substrate. 
 
     
     
       5. The method of  claim 1  wherein:
 the roughening of the surface comprises forming a plurality of peaks on the surface; and 
 the treating of the surface comprises flattening tops of at least a portion of the plurality of peaks. 
 
     
     
       6. The method of  claim 1  further comprising disposing a wavelength converting material over the treated surface. 
     
     
       7. A method comprising:
 roughening a light extracting surface of a semiconductor structure, the semiconductor structure comprising a light emitting layer; and 
 after the roughening, treating the surface to significantly reduce an amount of light extracted from the semiconductor structure through the surface. 
 
     
     
       8. The method of  claim 7  wherein treating the surface comprises treating the surface with plasma. 
     
     
       9. The method of  claim 8  wherein the plasma comprises at least one of Ar and O. 
     
     
       10. The method of  claim 7  further comprising:
 growing the semiconductor structure on a growth substrate; 
 attaching the semiconductor structure to a mount; and 
 removing the growth substrate; 
 wherein the light extracting surface is a surface revealed by removing the growth substrate. 
 
     
     
       11. The method of  claim 7  wherein:
 the roughening of the surface comprises forming a plurality of peaks on the surface; and 
 the treating of the surface comprises flattening tops of at least a portion of the plurality of peaks. 
 
     
     
       12. A method comprising:
 growing a semiconductor structure on a growth substrate, the semiconductor structure comprising a light emitting layer disposed between an n-type region and a p-type region; 
 removing the growth substrate; 
 roughening a light extracting surface of the semiconductor structure; and 
 treating the roughened surface with plasma, wherein the treating significantly reduces an amount of light extracted from the semiconductor structure through the roughened surface. 
 
     
     
       13. The method of  claim 12  wherein treating the roughened surface with plasma comprises treating the surface to increase total internal reflection at the surface. 
     
     
       14. The method of  claim 12  wherein treating the roughened surface with plasma comprises treating the surface to increase light absorption at the surface. 
     
     
       15. The method of  claim 12  wherein:
 the roughening of the surface comprises forming a plurality of peaks on the surface; and 
 the treating of the surface comprises flattening tops of at least a portion of the plurality of peaks. 
 
     
     
       16. The method of  claim 12  further comprising disposing a wavelength converting material over the surface. 
     
     
       17. The method of  claim 12 , wherein the amount of light extracted is reduced by at least 10% by the treating of the surface. 
     
     
       18. The method of  claim 7  further comprising disposing a wavelength converting material over the surface. 
     
     
       19. The method of  claim 7 , wherein the amount of light extracted is reduced by at least 10% by the treating of the surface.